28 



SELECTED "WESTERN FLORA 



2. P. balsamifera, L. Balsam Poplah. 



A larger tree than the preceding, with the bark becoming rougher as the 

 tree increases in size; buds large and smeared with a fragrant resin; leaves 

 ovate-lanceolate, taper-pointed. The tree commonly called black poplar or 

 Balm of Gilead, and widely distributed over the prairie region. Man.-Alta. 



3. P. deltoides, Marsh. Cotton-wood. 



A large tree with very rough bark and broad deltoid leaves on flattened 

 petioles often tinged with red ; stamens about 60 ; catkins long, easily drop- 

 ping, and spreading the seeds, which, being, furnished with copious down, 

 become very noticeable. River valleys, Man.-Alta. 



4. P. alba, L. White Poplar. 



Leaves oval, coarsely sinuate, toothed, densely white-woolly when young, 

 becoming smooth and dark green above. A 

 fair sized tree with the branches white-woolly 

 when young; often spreading from the root. 

 Introduced, but frequently used for orna- 

 mental purposes in Manitoba. 



Fig. 22. — Populus alba. 



Fig. 23. — Populus balsami- 

 fera (Western form). 



XIX. BETULACE^ (Birch Family). 



Monoecious trees or shrubs with alternate simple leaves and decid- 

 uous stipules; the sterile flowers in catkins, the fertile often in dense 

 cyUndrioal spikes; ovary 2-ceUed; styles 2. 



